The present invention relates to a new and improved apparatus for delivering powder, i.e., finely divided mineral adjuvants.
It has long been a problem in industry to deliver powder effectively from bags or containers to a point in a manufacturing process.
One method to deliver powder has been to use vacuum pipe suction. A vacuum pipe is placed into a container of powder and thereby picks up the powder in the container for delivery. The problem with this system is that the pipe must constantly be moved around in the container due to the bridging and caking of the powder, particularly in humid conditions. Another problem is that the flow through the pipe is very uneven since the powder in the container frequently has voids due to the aforementioned caking and bridging. Another problem is that the pipe picks up not only particles of powder, but also agglomerations of powder that have caked together. Such agglomerates may be very harmful to the manufacturing process to which the powder is being delivered. Finally, the pipe may also pick up foreign materials that might be in the container which can contaminate the manufacturing process.
The conveyance of powder is particularly important for the manufacturing processes that use powder. One such process, for example, is the manufacture of chewing gum base.
In the chewing gum base manufacturing process, the raw materials of the gum base are initially melted and mixed together. Then, the melted mix is blended and passed through a filter to take out any foreign materials or impurities. One filter system that may be used to filter the gum base melt comprises horizontal filter tubes, set up for easy and rapid cleaning, which are cylindrical in shape. The melt from the blender enters the filter cylinders from one end of the filter, then exits the filter on its sides through a cylindrical metal screen. The cylindrical metal screen is enclosed within a cloth sock that provides further filtering of the melt. Such filters are easily assembled and disassembled for cleaning purposes.
The filtered gum melt then falls from the filter into a receptacle and when required, is pumped through a heat exchanger to obtain a viscosity suitable for pelletizing.
After the melt passes through the heat exchanger it proceeds to a pelletizer. The pelletizer forms varying sizes of pellets from the gum melt. These pellets are formed by extruding the gum melt through a commercially available die with multiple openings. As the gum melt is extruded through the die, a knife cuts off the pellets. Various sized pellets can be obtained by varying melt temperature, pressure, and knife speed. High pressure water enters the chamber where the die forming the pellets is located. This high pressure water is typically at a temperature between 45.degree. F. and 70.degree. F. and has a flow of greater than 50 gallons per minute. It is directed to the surface of the die, to sweep the pellets rapidly away from the die.
The water and the newly formed pellets then travel through a pipe for a sufficient time to cool until arriving at the location where the pellets are strained from the pipe and the water is recirculated to the point where the pellets are initially formed. Cold water is added to the recirculated water at that point to maintain the required temperature.
The strained pellets are then dried by typical means known in the art. It is at that point that the pellets may proceed to a tumbler where the powder is mixed with the pellets. The powder is applied to the pellets to prevent adhesion, agglomeration, and the like before the pelleted gum base is eventually used in the production of chewing gum.
After the powder is added to the pellets, the pellets then move on through to a hopper and weigh scale at the end of the process. A typical hopper and weigh scale act to automatically fill boxes with the selected weight of pellets. Such a device contains two gravity loaders--one which operates at a high speed and the other at a low speed. In operation, the high speed loader and low speed loader dispense pellets to rapidly fill the box, and then the low speed loader operates alone to top off the final amount when the box is nearly full.